No epoxy is going to be a good enough heat conductor. =A0Get a piece of alu=
minum sheet and cut it to size. =A0Then stick the regulator to it with some=
 arctic alumina and let it cure. =A0Once that has completely cured, bend th=
e aluminum into a circular form that will fit tightly inside the plug. =A0B=
e careful not to break the regulator or snap it free from the heatsink whil=
e bending.

If that doesn't work, there are switchmode phone chargers out there with th=
e cigarette lighter plug and everything. =A0If you find the right one, ther=
e are 1 or 2 resistors that need to be changed to set it to 3.3V, that's it=
.. =A0You might have to cut the cord to add the right connector, but no furt=
her modifications are necessary. =A0Goodwill has baskets full of the things=
 for a dollar or two each.

Cheers,
Robert
----------------------------------------
> Date: Tue, 4 Mar 2014 11:26:14 -0500
> From: cdenk@windstream.net
> To: piclist@mit.edu
> Subject: [EE] Heat sinking a 3.3 VDC switching regulator
>
> The application is an auto power (cigarette lighter) power outlet plug
> containing a 3.3 VDC switching regulator to power a handheld GPS. The
> regulator is a:
> http://www.dimensionengineering.com/products/de-sw033
> which fits nicely in the plug housing. Initial testing using a 12 VDC
> bench supply was good, but when powered from 13.7 volt car battery,
> overheat caused the thermal protection to drop things out until it could
> cool down.
>
> The regulator has a 78XX pin out and a nice little aluminum heat sink.
> My first thought is to fill the housing cavity (1" dia.) with an epoxy
> or silicone with a bond breaker to the aluminum heat sink. After cure
> use a heat sink compound where the bond breaker was for good heat
> transfer. For the filler I'm thinking JBweld, but open to suggestions.
> Something with a good heat conduction. Would need to be something
> readily available. I do have a thin epoxy that I could add a filler, and
> have fine ground milled glass filler for it.
>
>
> Any thoughts appreciated. :)
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